What the Trump campaign revealed, as Republicans and even Democrats moved toward him on trade, immigration and foreign policy, is that Bush Republicanism and neoconservatism not only suffered a decisive defeat, they had a sword run right through them.

Trump won the nomination, he won the argument, and he won the debate. The party is now with Trump—on the issues. For GOP elites, there can be no going back to what the grass roots rejected.

What does this suggest for Trump himself?

While he ought to keep an open door to those he defeated, the greatest mistake he could make would be to seek the support of the establishment he crushed by compromising on the issues that brought out his crowds and brought him his victories and nomination.

Given Trump's negatives, the Beltway punditocracy is writing him off, warning that Trump either comes to terms with the establishment on the issues, or he is gone for good.

History teaches otherwise.

Hubert Humphrey closed a 15-point gap in the Gallup poll on Oct. 1 to reach a 43-43 photo finish with Richard Nixon in 1968.

President Gerald Ford was down 33 points to Jimmy Carter in mid-July 1976, but lost by only 2 points on Election Day.

In February 1980, Ronald Reagan was 29 points behind Jimmy Carter, whom he would crush 51-41 in a 44-state landslide.

Gov. Michael Dukakis left his Atlanta convention 17 points ahead of Vice President George H. W. Bush in 1988. Five weeks later, Labor Day, Bush had an eight-point lead he never lost, and swept 40 states.

What this suggests is extraordinary volatility of the electorate in the modern age. As this year has shown, that has not changed.

How then should Trump proceed?

Unify the party, to the degree he can, by keeping an open door to the defeated and offering a hand in friendship to all who wish to join his ranks, while refusing to compromise the issues that got him where he is. If the Bushes and neocons wish to depart, let them go.

Lest we forget, Congressman John Anderson, who lost to Reagan in the primaries, bolted the party and won 7 percent of the national vote.

Ted Cruz, who won more states and votes than all other Trump rivals put together, should be offered a prime-time speaking slot at Cleveland—in return for endorsing the Trump ticket.

As the vice presidential nominee remains the only drama left, Trump should hold off announcing his choice until closer to Cleveland.

For while that decision will leave one person elated, it will leave scores despondent. And the longer Trump delays his announcement, the more that those who see themselves as a future vice president will be praising him, or at least holding off from attacking him.

Ultimately, the Great Unifier upon whom the Republican Party may reliably depend is the nominee of the Democratic Party—Director James Comey and his FBI consenting—Hillary Rodham Clinton.